1. Field of the Invention
This invention relates to systems for converting electrical signals into sound patterns and more particularly to systems which can convert the visual readout of an instrument such as an oscilloscope into a sound pattern representative of the visual readout.
2. Discussion of Related Art
The vast majority of instruments used for measuring and testing applications use visual readouts to indicate the quantity being measured. Such instruments, such as an oscilloscope, are invaluable in certain fields of endeavor. However, these instruments have certain drawbacks. First, it is necessary that a user focus his or her attention on the visual readout in order to be constantly aware of the status of the measured quantity. Therefore, if the user wishes to make adjustments to a system containing the measured parameter, he or she must either make the adjustments without keeping careful track of the effect of the adjustment as indicated on the visual readout, or must constantly watch the readout and make the adjustments only by physically feeling the elements being adjusted.
Furthermore, these instruments cannot be used by persons handicapped by limited sight. If such a person is to use, for example, an oscilloscope, he or she must have someone else provide an aural description of the status of the visual readout.
Consequently, it would be useful to have a system which can directly produce an audible representation of a measured parameter in order to replace or augment a measuring instrument such as an oscilloscope. Such an instrument could produce a sound pattern representative of the visual pattern of an ordinary oscilloscope or other measuring and testing instrumentation.
Systems are already known for producing sound pattern representations of certain quantities. For example, U.S. Pat. No. 3,007,259 to Abma et al shows an optophone which comprises an optical head that can be passed over printed material. The system produces a unique sound pattern for each letter of the alphabet to enable a sightless person to read the printed material aurally.
U.S. Pat. No. 3,800,082 to Fish discloses a system for producing sound patterns representing various objects wherein the raster scan display of an oscilloscope CRT is detected by a photomultiplier tube. The object to be represented is placed between the CRT and photomultiplier tube. The signal from the multiplier tube causes a sound to be generated representing the position of the illuminated portion of the oscilloscope CRT which is not covered by the object.
U.S. Pat. No. 3,907,434 to Coles discloses a binaural sight system in which two cameras are used which generate image signals representative of optical images projected thereonto. The cameras are positioned in horizontally spaced relation and are independently connected to right and left earphones. The cameras are scanned in opposite directions and the output from the cameras are used to drive the earphones
U.S. Pat. No. 4,000,565 to Overbee et al discloses an apparatus for converting silent digital visual display characters into sequentially enunciated audible tones which blind or visually handicapped persons can recognize.